Liquid Fertilizer

  • Common Concentrations in Nutrients

    Orchilla Guano A A The great soil enricher
    Boston Public Library, Print Department

    The composition of hydroponic fertilizers is completely different compared to the fertilizers for earth cultures. Plants that are cultivated in soils require completely different fertilizer mixtures than hydroponics. As a guide: Organic fertilizers often need microorganisms (depending on their composition) to break down the nutrients for the plants. Inorganic fertilizers do not need microorganisms to be able to supply the plant with all nutrients. Of course, the following also applies here: the exception confirms the rule.

    Hydroponic fertilizers must be accountable for the special conditions of a hydroponics. These result on the one hand from the lack of microorganisms, which are required for the chemical splitting of the fertilizer substances in the soil - and can only be found there, on the other hand from the lack of buffering of the hydroponic system and from the fact that it is a closed system.

    Important boundary conditions include: Hydroponic fertilizers should not contain too many ballast salts (sodium, chloride, etc.). The ammonium and nitrogen content should not account for more than about 50% of the total nitrogen (N) supply in order to avoid acidification of the nutrient solution.

    However, this in turn does not apply to very hard (lime-rich) irrigation water. The phosphate content should also be significantly lower - compared to fertilizers for earth culture.

     

    Fertilizer with buffer effect / reservoir or so-called long-term fertilizer

    There are ion exchange fertilizers on the market for hydroponics. For decades, the ion exchange fertilizer “ Lewatit HD5 ” has been the only ion exchange fertilizer on the market. It was developed by Bayer AG in the 1970s and marketed under various trade names. The same company later developed the “ Lewatit HD5 plus ” for low-salt irrigation water (soft water).

    In the meantime, only the well-known Lewatit HD50 is manufactured. This should be optimized for every degree of hardness of the water. However, the manufacturer still recommends adding lime to soft water to ensure supply. 

     

    Which liquid fertilizer can you use?

    The range of liquid fertilizers and nutrient solutions has now become unmistakable (1). In addition to liquid fertilizers for the professional in larger containers, products are offered in smaller quantities for the hobby area. Mostly they are so-called universal fertilizers. However, some manufacturers also offer special fertilizers for hydroponics.

    Striking here: almost all manufacturers hold back with specific information about the plants for which the fertilizer should be "optimal. Likewise in dosing depending on the growth development. Even if certain plants are named by name, apparently not detailed here. If you think of tomatoes, you will probably not think of all 3,200 varieties that are currently being grown (source). To believe that one and the same fertilizer delivers consistently good results here also seems completely unbelievable to the layperson.

    1) You can find a (always) incomplete list of commercially available fertilizers here. We only keep this list as a list of ingredients for homemade nutrient solutions. You can find out how to do this here in detail using a sample mix. The series of articles begins here: Mix the hydroponic fertilizer yourself: introduction

     

    There are several ways to fertilize plants in hydroponics:

    • With liquid inorganic solid fertilizer, this is automatically added in large plants due to the conductivity measurement of the water.

    • By fertilizer salt release from solid ion exchanger granules.

    • Sludge up organic fertilizer or add such nutrient solutions.

    • A humus or compost layer that is applied to the top substrate layer in low-fiber systems and is only watered from above when fertilizer is required.

    Depending on the nutrient composition, the expected concentrations are of the following orders of magnitude:
     

    Compounds and trace elements / orders of magnitude in nutrient solutions

    K

    potassium

    0.5 - 10 mmol / L

    Ca

    Calcium

    0.2 - 5 mmol / L

    S

    sulfur

    0.2 - 5 mmol / L

    P

    phosphorus

    0.1 - 2 mmol / L

    Mg

    magnesium

    0.1 - 2 mmol / L

    Fe

    iron

    2 - 50 µmol / L

    Cu

    copper

    0.5 - 10 µmol / L

    Zn

    zinc

    0.1 - 10 µmol / L

    Mn

    manganese

    0 - 10 µmol / L

    B

    boron

    0 - 0.01 ppm

    Mon

    Molybdenum

    0 - 100 ppm

    NO2

    nitrite

    0 – 100 mg / L

    NO3

    nitrate

    0 – 100 mg / L

    NH4

    ammonia

    0.1 - 8 mg / L

    KNO3

    Potassium nitrate

    0 - 10 mmol / L

    Ca ( NO3 ) 2

    Calcium nitrate

    0 - 10 mmol / L

    NH4H2PO4

    Ammonium dihydrogen phosphate

    0 - 10 mmol / L

    ( NH4 ) 2HPO4

    Diammonium hydrogen phosphate

    0 - 10 mmol / L

    MgSO4

    Magnesium sulfate

    0 - 10 mmol / L

    Fe-EDTA

    Ethylenediaminetetraacetic acid

    0 – 0.1 mmol / L

    H3BO3

    Boric acid

    0 – 0.01 mmol / L

    KCl

    Potassium chloride

    0 – 0.01 mmol / L

    MnSO4

    Mangan (II)-Sulfat

    0 – 0,001 mmol/L

    ZnSO4

    Zinksulfat

    0 – 0,001 mmol/L

    FeSO4

    Eisen(II)-sulfat

    0 – 0,0001 mmol/L

    CuSO4

    Kupfersulfat

    0 - 0,0002 mmol/L

    MoO3

    Molybdänoxid

    0 – 0,0002 mmol/L
     
     

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  • Nutrient solution: The simplest Solution

    Here is a recipe for small systems that supply tomatoes, peppers and leafy vegetables:
     
    Ingredients
    Base with micronutrients/trace elements: Masterblend 4-18-38 Hydroponic Fertilizer: this is still missing magnesium sulfate and calcium nitrate.
    One kilo costs about 30 to 49 euros and is enough for about 1500 liters of nutrient solution
     
    Magnesium sulfate: Epsom Salt
    One kilo costs about 5 euros 
     
    Calcium nitrate: PowerGrow Calzium Nitrate 15.5-0-0
    One kilo costs about 24 euros 
    Recipe
    Mix the ingredients in the following ratios: (2:1:3). You must not mix all the ingredients together .
    To do this, take two containers (bottles) of 500 ml each. This will prevent the calcium nitrate from reacting with the phosphate and precipitating.
     
    Fill the first bottle with 120 grams of NPK fertilizer and 60 grams of magnesium sulfate. If you use warm water (preferably deionized or distilled), the components dissolve better. Remember that tap water already contains calcium and magnesium. Depending on the water hardness, you should reduce the amount of calcium and magnesium. One °dH corresponds to 10 mg CaO (calcium oxide) per liter of water.
     
    Contents  division
     120 grams of Masterblend 4-18-38 (about 1/2 cup and a tablespoon) 
     60 grams of magnesium sulfate (about 4 tablespoons)
    		  Solution 1: mix with 500 ml water
     180 grams of calcium nitrate (about 3/4 cup)  Solution 2: mix with 500 ml water
     
     
    Use / Concentration
     Plant  concentration 
     Fruit-bearing bedding plants
     Solution 1: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Solution 2: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Green leafy vegetables  Solution 1: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     Solution 2: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     
    When mixing the nutrients, pay attention to whether the plants show any signs of deficiency. Read more here: Signs of deficiency.
    If you have an EC or TDS meter, the concentration should be between 1.5 and 2.0 EC. Read more here: EC and pH values ​​of plants.
     
    * ) Conversion
    1 US gallon = 3.78541 liters = 231 cubic inches (inch³)
    1 liter = 0.26417 US gallons
    1 American gallon = 4 American quarts = 8 American pints = 3.785411784 liters
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    ID: 595
     

  • pH and Ec Finder

    john deere California Agricultural Museum pd s

    Here you can view the plants that have similar pH and Ec values ​​and can therefore, at least in this respect, be planted together in an aqua or hydroponic system. Also pay attention to the temperature.

    What are the nutrient requirements for certain plants? This list shows the nutrient concentration preferred by each plant. Note the differences within the subspecies/breeding . Please remember: there are 23,000 varieties of tomatoes - of course these vary in terms of preferred temperatures as well as Ec and pH values! The fine-tuning of the nutrient composition is not even mentioned here. More details about the list at the end of the same.

     

     

     

    You can also download the list of pH and Ec values here. This list should only serve as an orientation and does not save you from a detailed check of your cultivation. Don't forget that even within the same subspecies the differences can be very big. And of course we do not take any responsibility for the information given. We also offer a precise determination of the nutrient requirements for your plants and can thus provide you with a nutrient roadmap.

    Download as: TabCalc CSV, TabCalcXLSX, TabCalcODS, TabCalcText, TabCalcPDF 

     

    The Ec value

    We measure the salt concentration with an Ec, TDS or PPM measuring device. The nutrients dissolve in the water and provide a value measured by the EC or PPM measuring device that shows you how much fertilizer is contained in the nutrient liquid and therefore how much fertilizer needs to be added if necessary.
     
    As soon as the Ec value drops, you need to fertilize accordingly. You can measure, check and control this every minute with one of our systems  or by hand with an Ec pH measuring device . The advantage of the control system is obvious: with minimal steps in the supply of the nutrient solution through a micropump, you can always maintain the exact range that is optimal for the plant.
     
    If the Ec value increases, you simply need to add more water to the nutrient solution. A rising Ec value can have many reasons: contamination from the plants themselves, water that is too rich in minerals, accidental overdose, etc.
     
     

    The pH value

    If the pH value falls below the recommended value (towards acidic / pH 1), you can use a basic solution to correct the pH value back towards basic (pH 14). 
     
    If the pH value rises above the recommended value (towards basic / pH 14), you can correct the pH value back towards acidic (pH 1) with an acidic solution. You can measure, check and control this every minute with one of our systems  - but we have already mentioned that.
     
    According to the old school wisdom: Acid + alkali equals salt + water, you can use anything from household vinegar (acid) to baking soda/soda (base) to correct the pH in one direction or the other. But: as mentioned, salts are formed. These of course change the Ec value. At this point in the process you have to observe the plants closely in order to detect any deficiency symptoms in good time.
     
    If you only have 50 or 100 plants, a complete replacement of the nutrient solution is always the safe way. As a guide: 100 tomato plants consume around 5 liters of fertilizer concentrate in three months in an outdoor area with around 150 liters of water/nutrient solution (central Portugal, mid-summer). In large systems, it is preferred to analyze the current nutrient solution in order to simply supplement the missing components in a targeted manner.
     
    The pH and electrical conductivity values ​​( Ec, TDM, PPM values) given here are guidelines only. Your specific requirements for plant cultivation vary depending on the subspecies of the plant, growth phase and many other factors (UV value, brightness, lighting duration, genus/breeding/subspecies, temperature, etc.). For hydroponics use inorganic fertilizer, for soil use organic. The organic fertilizer requires microorganisms to break down the nutrients. These microorganisms are missing in hydroponics.
     
    The values ​​mentioned here are only for hydroponic plants (ground plants sometimes differ greatly). Almost all plants tolerate slight over or under concentrations in soil. The plant “consumes” different amounts of the individual substances (nutrients). If the nutrient solution is not optimally composed, deficiency symptoms can quickly occur. With general nutrient solutions or fertilizer mixtures, the entire nutrient solution usually needs to be replaced every three to four weeks. An analysis of these small quantities is in any case more expensive than the amount of fertilizer you pay instead.
     

    The temperature

    Temperature greatly influences the Ec and pH of the nutrient solution. Most pH meters therefore have automatic temperature compensation. Some EC and pH meters come with a bag containing a calibration liquid that can be used to calibrate the meter. Depending on the quality of the sensors used, this should be done every few weeks. We strongly recommend that hobbyists join one or more hydroponic community forums. 
     

    Below are some articles to further delve into the subject...

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